The organ of Corti is composed of a variety of cell types including sensory, supporting and neural elements. Taken together, these cells comprise a functionally intricate and cohesive electrical unit which initiates the analysis of acoustic information within our environment. The outer hair cell (OHC) is believed to be responsible for our enhanced ability to resolve acoustic information. During the last few years the in vitro approach has aided in the elucidation of cell function; the strategy is to understand the cells first on an individual basis, and finally to integrate this knowledge into a complete understanding of the organ of Corti. The overall aim of this project is to analyze the membrane properties of isolated cell types (spiral ganglion cells, supporting cells, and OHCs ) from the inner ear using the whole cell voltage clamp technique, and video analysis of the OHC mechanical response. Specifically, we intend to 1) study the ionic conductances of spiral ganglion cells, 2) study in detail and make modifications to the electrical correlate of OHC motility, its nonlinear capacitance, 3) analyze what such modifications will do to the high frequency mechanical activity of the OHC, 4) determine compartmentalization of the ionic conductances and motility voltage sensors within the membrane of the OHC, and 5) continue analyzing control mechanisms of cell coupling in supporting cells. These results will lead to a deeper understanding of inner ear function and aid in understanding auditory pathologies which may result from OHC insult and homeostatic imbalance, including sensorineural hearing loss and tinnitus.